The instant invention relates to wire payoff apparatus and more particularly to an improved wire payoff apparatus of the general type wherein wire is payed off from a spool by passing it over a rotating payoff cap on a payoff end of the spool.
Wire payoff apparatus of the general type disclosed in the U.S. Pat. No. 4,135,679, to MURPHY et al, have been found to be highly effective for paying off wire from spools prior to coating or otherwise processing the wire. An apparatus of this general type normally comprises first and second spools containing quantities of wire wound thereon in predetermined wound directions, first and second payoff caps on predetermined payoff ends of the spools, and first and second payoff cap rotating mechanisms for rotating the payoff caps relative to the spools. The payoff caps of an apparatus of this type normally comprise caps of the general type disclosed in the U.S. Pat. Nos. 3,997,127; 4,017,037 and 4,055,314 to KOVALESKI; and they are operative for providing slight resistances to wire payed off from spools thereof as the wire passes over the payoff caps. In this connection, the payoff caps of an apparatus of this type are normally rotated in directions which are opposite the wound directions of the wire on the spools thereof so that the caps rotate in the same directions as the wire as it flips around the caps thereof during payoff. An apparatus of this general type further includes first and second tapered enclosure drums around the spools thereof, the enclosure drums including enlarged first ends and reduced second ends having terminal apertures therethrough. The enclosure drums of an apparatus ratus of this type are assembled over the spools thereof so that the spools can be observed through the enlarged open ends of the drums and so that wire can be payed off the spools by passing it over the payoff caps thereof as it is drawn outwardly through the apertures in the reduced ends of the drums. Further, the drums generally have elongated slots in the inwardly facing or opposed sides thereof which extend to the terminal apertures in the payoff ends thereof so that a lead wire from the inner or hub end of one spool can be connected to the wire on the other spool to enable payoff to be automatically transferred from one spool to the other spool when the wire on the original spool has been fully payed off. An apparatus of this type generally further comprises a brake assembly which alternatively receives wire from the first drum or the second drum for applying increased tension thereto as it is drawn from the apparatus.
During use of an apparatus of this type, wire is normally drawn from the brake assembly so that the wire is drawn outwardly from one of the enclosure drums and paid off from the spool therein by passing over the payoff cap on the spool. As wire is paid off from a spool in this manner, the payoff cap thereon is rotated at a speed which is just slightly less than the flip speed at which the wire passes around the payoff cap so that the payoff cap applies a slight amount of resistance to the wire as it is payed off. In this connection, however, it has been found that since the wound diameter of a spool of an apparatus of this type is inherently decreased as wire is payed off therefrom, the flip speed of the wire as it passes over the payoff cap on the spool is inherently increased during the course of the payoff as long as wire is payed off at a substantially uniform rate. Accordingly, it has been found that it is generally necessary for an operator of an apparatus of this type to closely monitor the flip speed of a wire as it is paid off from a spool by looking through the open end of the appropriate enclosure drum and to frequently adjust the speed of the payoff cap on the spool therein so that it is maintained at a level which is just slightly less than the flip speed. It has also been found that as the wound diameter of a spool of an apparatus of this type is decreased, the average angle at which wire from the spool approaches the payoff cap thereof is inherently changed so that the resistance which is applied to the wire as it passes over the cap is increased correspondingly. Accordingly, it has also been found that it is generally necessary for an operator of an apparatus of this type to closely monitor the wound diameter of the spool from which wire is being payed off and to frequently adjust the brake assembly in order to maintain the overall tension applied to a wire by the apparatus at a substantially uniform level. Unfortunately, however, it has been found that manual adjustments of this type are often neglected and that they are often imprecise when carried out. Further, it has been found that while two-spool payoff apparatus of the above described type have generally had the advantage that they enable an empty spool to be replaced while wire is being payed off from the other spool, it is not uncommon for an operator of an apparatus of this type to neglect to change an empty spool before the wire is completely payed off from both spools. When this occurs, it is generally necessary to shut down the apparatus along with any related downstream processing equipment in order to replace both spools and to feed a new wire through the apparatus and through the related downstream processing equipment. Still further, it has been found that it is not uncommon for an operator of an apparatus of this type to forget to actuate the payoff cap of a new spool before payoff is transfered to the new spool so that irregular tension is applied to the wire which can be detrimental to the operation of downstream processing equipment.
The instant invention provides an improved wire payoff apparatus which overcomes many of the disadvantages of the heretofore available payoff apparatus. The apparatus of the instant invention is preferably embodied as a two-spool payoff apparatus, although it will be understood that it can also be embodied as a single-spool payoff apparatus for paying off wire from a single spool. The preferred embodiment of the apparatus of the instant invention comprises first and second wire spools having rotatable payoff caps thereon, first and second rotating mechanisms for rotating the first and second payoff caps, respectively, and first and second enclosure drums around the first and second spools, respectively. The apparatus further comprises a brake assembly for alternatively receiving wire from the first drum as it is payed off the first spool or from the second drum as it is payed off the second spool, and the enclosure drums of the apparatus are adapted to permit payoff to be automatically transferred from the first spool to the second spool. The apparatus still further comprises first and second diameter sensors for sensing the wound diameters of the first and second spools, respectively, first and second payoff sensors for detecting the payoff of wire from the first spool and the second spool, respectively, a line speed sensor for sensing the rate of payoff from the apparatus, and a control which is responsive to the first and second diameter sensors, the first and second payoff sensors and the line speed sensor for controlling the cap speeds of the first and second payoff caps, respectively, and/or the brake assembly in order to operate the apparatus so that a substantially uniform degree of tension is applied to a wire drawn from the apparatus. The control is preferably operative for maintaining the ratio between the rotational speed of the payoff cap of the spool from which wire is being payed off and the flip speed of the wire passing over the same payoff cap at a substantially uniform level with the cap speed being slightly less than the flip speed. Further, the first control is preferably operative so that when the wound diameter of one of the spools reaches a predetermined level as wire is being payed off, the control actuates the cap rotating mechanism on the other spool if the wound diameter of the other spool exceeds a predetermined minimum value but so that it effects a controlled shut down of the spool from which wire is being payed off as well as any operatively connected down stream processing equipment if the wound diameter of the other spool is below the predetermined minimum value. Still further, the apparatus preferably comprises first and second indicating mechanisms which are responsive to the first and second diameter sensors, respectively, for indicating the amounts of wire on the first and second spools, respectively; and since visual monitoring of the spools is unnecessary, the apparatus preferably further comprises first and second end plates for substantially closing the enlarged ends of the enclosure drums in order to reduce noise emitted from the apparatus.
Accordingly, it is a primary object of the instant invention to provide an effective payoff apparatus which includes a diameter sensor for sensing the wound diameter of a payoff spool and a control which is responsive to the diameter sensor for controlling the rotational speed of a payoff cap on the spool.
Another object of the instant invention is to provide a payoff apparatus which includes a diameter sensor for sensing the wound diameter of a spool, and a control for controlling a brake assembly of the apparatus to reduce the amount of tension applied by the brake assembly to a wire drawn through the apparatus as the wound diameter of the spool is decreased.
An even further object of the instant invention is to provide an effective wire payoff apparatus which is automatically operative for applying a substantially uniform degree of tension to a wire drawn from the apparatus.
An even further object of the instant invention is to provide an effective wire payoff apparatus which is operative at a reduced sound level.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.